The Effect of Rhinoplasty Dissection Planes (Sub-SMAS, Subperichondrial, and Subperiosteal) on the Viability of Diced Cartilage Grafts in a Rabbit Model

Overview

Surgeons choose which tissue layer to lift when exposing the nose. Deeper planes, subperichondrial and subperiosteal, have spread with preservation rhinoplasty because they reduce swelling and speed healing. Whether those planes affect the survival of cartilage grafts placed in them was unknown. The authors placed diced cartilage in each of three planes in a rabbit model and examined the tissue microscopically after 90 days.

Sections of note

• Design: rabbit study, three planes compared, tissue examined 90 days after graft placement.
• Viability was judged by loss of cartilage cell nuclei, new cell growth at the graft edge, and loss of matrix staining.
• Median live cell percentages: 67.5 percent sub-SMAS, 35 percent subperichondrial, 20 percent subperiosteal, p equal to 0.001.
• Median peripheral cell proliferation: 80.0 percent sub-SMAS, 30 percent subperichondrial, 20 percent subperiosteal, p equal to 0.001.
• Between group testing showed the difference lay between sub-SMAS and the two deeper planes.
• Less loss of cartilage matrix was seen in the sub-SMAS group, p equal to 0.006.

What it means for a patient

• Where a graft is placed appears to matter as much as what it is made of. The more superficial plane kept far more cartilage cells alive.
• This finding runs against the trend toward deeper dissection planes when a cartilage graft is part of the plan, so the two goals may conflict.
• Limits: rabbit cartilage, blood supply and healing differ from human, and no clinical outcomes were measured. Cell survival at 90 days does not prove a graft holds volume in a human nose over years.

Why this paper matters

Diced cartilage is a mainstay for smoothing and augmenting the bridge, and resorption is its recognized failure mode. Linking graft survival to the surgical plane gives a mechanism a surgeon can act on. Whether the same relationship holds in humans, and whether it translates into visible volume loss, is untested.

Terms

• Diced cartilage: cartilage cut into tiny pieces so it can be molded like a paste.
• SMAS: the superficial musculoaponeurotic system, a fibrous layer beneath facial skin.
• Sub-SMAS plane: dissection just below that fibrous layer, above the cartilage covering.
• Subperichondrial plane: dissection beneath the membrane covering cartilage.
• Subperiosteal plane: dissection beneath the membrane covering bone.
• Chondrocyte: the cell type that maintains cartilage.